Curtain bag

ABSTRACT

Provided is a curtain bag which can be brought into an inflated state as required in a short time without locally applying an excessive load to its outer peripheral joint part ( 1 ) and inner joint parts ( 2 ). The dot-like inner joint parts ( 2 ) on the inside of the outer peripheral joint part ( 1 ) are isolated from the outer peripheral joint part ( 1 ) and also made to be independent of each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.12/664,636 filed on Dec. 14, 2009, now U.S. Pat. No. 8,276,938 which isa National Phase application of PCT/JP2008/062138 filed on Jul. 4, 2008,which claims the benefit under 35 U.S.C. §119(a) to Japanese PatentApplication Nos. 2007-181838; 2007-257060; 2007-322147 and 2008-020076all filed in Japan, on Jul. 11, 2007; Oct. 1, 2007; Dec. 13, 2007 andJan. 31, 2008, respectively. The entire contents of all of the aboveapplications are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a curtain bag (also, called aninflatable curtain or a curtain air bag), which bag is caused to inflatebetween a side window of an automobile and a passenger to absorb a shockon a passenger's head in order to protect a passenger's head mainly whena side of an automobile collides against another automobile or anobstacle.

BACKGROUND ART

Most passenger cars presently produced are provided with a so-calleddriver seat air bag and an assistant driver seat air bag, each of whichis caused to rapidly inflate between a passenger and a cab structure inan automobile when the front face of the automobile collides (head-oncollision) against another automobile or an obstacle.

In recent years, in order to protect a passenger's head not only inhead-on collision but also when a side of an automobile collides(lateral collision) against another automobile or an obstacle, a curtainbag system begins to be really mounted, in which system a curtain bagfolded and stored in a ceiling part above a side window of an automobileor a pillar part develops and inflates in a manner to cover a sidewindow portion in a collision.

Conventionally, a curtain bag shown in Patent Document 1 is known as anexample of a curtain bag. As shown in FIG. 19, the curtain bag shown inthe Patent Document 1 comprises two pieces of cloth provided with acoating and joined at an outer peripheral joint part 101 provided atouter peripheral edges thereof to define an outer peripheral shape of abag, and at an inner peripheral joint part 102 provided inwardly of theouter peripheral joint part 101. The inner peripheral joint part 102defines an inflated shape of an inflating portion (a portion inflated byintroduction of gases) and is provided to assume a linear, curvilinear,or U-shaped configuration, which consists of a combination of the formertwo configurations, continuous to the outer peripheral joint part 101.Also, the curtain bag shown in the Patent Document 1 includes a gasinflow port 103, to which a gas generator (inflator) is connected, on arear and upper portion of the bag.

Also, conventional curtain bags include ones having an inner joint part,which is independent of an outer peripheral joint part and shown in FIG.20 in Patent Document 2, or FIG. 21 in Patent Document 3.

In forming the outer peripheral joint part and the inner joint part, asystem by means of machine-sewing and a system (referred below to as OPWsystem), in which a weaving machine on which a Jacquard machine ismounted is made use of to cross threads in predetermined positions andin a predetermined configuration at a weaving stage to form a jointpart, are put to practical use. Also, there exists a type, in which agas inflow port is provided on an upper portion of a bag. Further,curtain bag systems include ones of two kinds, that is, one (firstimpact accommodating type), in which a passenger is simply protectedimmediately only after lateral collision, and one (roll overaccommodating type), which takes account of protection of a passengeralso in the case where an automobile turns sideways after lateralcollision.

-   Patent Document 1: U.S. Patent Specification No. 60/10,149-   Patent Document 2: German Utility Model Specification No. 29903409-   Patent Document 3: U.S. Pat. No. 5,566,977

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

By the way, in case of assuming a lateral collision, a distance betweena passenger and a structure in an automobile compartment, against whichthe passenger is struck, corresponds to a distance between the passengerand a lateral window. The distance is small as compared with a distancebetween a passenger on a driver's seat and a steering wheel and adistance between a passenger on an assistant driver's seat and aninstrument panel in case of assuming a frontal collision. Therefore, itis required as one of important performances demanded to a curtain bagto develop from a folded state in a short period of time, to have gasesflowing appropriately into a necessary part, and to inflate up to apredetermined internal pressure until a passenger's head comes intocontact with the bag.

With conventional curtain bags, however, several, comparatively largeinflating portions are formed from a small number of inner joint partsassuming a linear, curvilinear, or U-shaped configuration, whichconsists of a combination of the former two configurations, continuousto the outer peripheral joint part. Therefore, gases in the bag aresmall in flow speed and so it is difficult to distribute gases from agas generator to inflating portions in a short period of time. Inparticular, with a curtain bag, in which inner joint parts are U-shapedto form inflating portions called cells or cabins, there is generated aphenomenon that a certain cabin inflates but other cabins, which shouldinflate, are still in the course of inflation.

Also, since gases from a gas generator cannot be quickly andappropriately distributed, an increase in internal pressure is locallygenerated, so that an excessive load applies on outer peripheral jointparts and inner joint parts around the pressure increased portions.Further, since conventional curtain bags comprise several inflatingportions and one inflating portion is large in volume, loads to beapplied on outer peripheral joint parts and inner joint parts increase.

Also, with conventional curtain bags having inner joint parts beingindependent of outer peripheral joint parts, inflating portions having auniform size are formed to be uniformly arranged irrespective oflocations on the curtain bag as shown in FIGS. 21 and 22. Therefore, theindependent inner joint parts act as resisting portions to gas flow froma gas generator, an excessive stress is generated there and gases leakfrom the portions, so that it is difficult to maintain the function ofan air bag.

Also, since a portion of the bag, which is not needed to inflate, forexample, a portion corresponding to a pillar portion of an automobileinflates also in the same manner as protect portions, wasted gases areneeded, so that a large-sized gas generator is made necessary. Further,with conventional curtain bags, in which independent inner joint partsare uniformly arranged irrespective of locations on the curtain bag, apillar portion and inflating portions inflate uniformly, so that acurtain bag is increased in volume of inflation, inflation speed becomesslow, and gas flow passages of inflating portions positioned in thepillar portion are large, so that the flow speed of the gases becomesslow and gases being supplied to those inflating portions, which shouldbe protected, also becomes slow.

Accordingly, with conventional curtain bags, since an increase ininternal pressure is locally generated and inflating portions are largein volume, an excessive load is liable to apply on the outer peripheraljoint parts and the inner joint parts, so that the bag burstsoccasionally in the course of inflation. Also, even when burst does notoccur, gases flow out due to partial breakage and peeling-off of acoating film and so a predetermined internal pressure required forprotection of a passenger is not obtained in some cases. In particular,with roll over accommodating type bags, it is occasionally difficult tomaintain a predetermined internal pressure for a predetermined period oftime.

Therefore, there exists also a method of reducing the phenomenondescribed above by means of mounting a gas distributing member, which isgenerally referred to as inner tube, to a conduit tube of a gasgenerator in a bag. However, the bag becomes heavy, decreases ineasiness in storage, and increases in cost. Also, with bags of OPWsystem, in order to cope with the phenomenon described above, it hasbeen intended to increase strength of a woven fabric and it has beenintended to prevent gas leakage due to sieve opening of the outerperipheral joint parts and the inner joint parts. However, for thepurpose of them, it is required that a woven fabric of high density beformed from threads of high fineness and a large quantity of coatingagent be applied. Also, with machine-sewing type bags, reinforcement ispartially accomplished and a thick sealing material is interposed andsewn between two pieces of cloth about the outer peripheral joint partsand the inner joint parts. In either case, as a result of such disposal,bags are made heavy, bulky and poor in easiness of storage, and increasein cost.

With conventional curtain bags, inflating portions are frequently formedfrom U-shaped cabins as shown in FIG. 22. With bags of such shape, thepossibility that an outer peripheral joint part 101 and an innerperipheral joint part 102 are formed is high in specified warp and/orspecified weft as in a region indicated by X in the figure as comparedwith other warps and/or specified wefts. In addition, the referencenumeral 103 in FIG. 22 denotes a gas inflow port.

An outer peripheral joint part and an inner peripheral joint part of acurtain bag of OPW system are woven into one cloth by crossing weavingyarns of two cloths and two times in density of weaving that ofinflating portions, in which two pieces of cloth are separate from eachother, so that the outer peripheral joint part and the inner peripheraljoint part are greater in bending rate of weaving yarn than theinflating portions. Therefore, warp threads (or weft threads), whichfrequently form the outer peripheral joint part and the inner peripheraljoint part, are woven at a weaving stage with a high tension as comparedwith warp threads (or weft threads), which less frequently form theouter peripheral joint part and the inner peripheral joint part, so thatstrain is present in a woven fabric to generate draw and wrinklesbetween the both. Such draw and wrinkles are responsible fordisadvantages in subsequent processes. Such draw and wrinkles areresponsible for generation of unevenness in coating of a coating agentin, for example, a coating process, and are responsible for generationof failure in cutting to a predetermined geometry in a cutting process.

Also, in the case where a rate, at which the outer peripheral joint partand the inner peripheral joint part are concentrated on certain warpthreads (or weft threads), is high, stress concentration is liable tooccur at boundaries between the outer peripheral joint parts and theinner peripheral joint parts, and the inflating portions at a stage, atwhich the bag inflates, the portions becoming an origin of breakage ofthe bag in some cases. With machine-sewing type bags, since an ordinary,plain weave fabric is woven and two pieces of cloth are sewn after acoating processing and cutting, strain at a weaving stage is notinternally present as in the OPW system, but in the case where a rate,at which the outer peripheral joint part and the inner peripheral jointpart (sewn portion) are concentrated on certain warp threads (or weftthreads), is high, the outer peripheral joint part, the inner peripheraljoint part, and the inflating portions are different in load-elongationpercentage characteristics, so that stress concentration is liable tooccur in the portions in the same manner as described above.

Further, since conventional curtain bags comprise several, innerperipheral joint parts, it is necessary to determine the design of thebag according to a shape, in particular, a roof configuration of anautomobile and a position, in which a passenger is seated, so that ahead injury criteria of a dummy becomes equal to or less than areference criteria in a crash test. Therefore, a great deal of manhourand a long period of time are required in design and testing fordetermination of a bag configuration every vehicle classification.

Also, it suffices according to current regulations that a sittingposture of a dummy be a prescribed, normal sitting posture and satisfy acriteria of injury, but a passenger's sitting posture is very various toinvolve the possibility that an adequate protective effect cannot beexpected according to a posture.

It is an object of the invention to obtain a necessary inflated state ina short period of time in a curtain bag without local application of anexcessive load on the outer peripheral joint part and the inner jointpart.

A further object of the invention is to provide a curtain bag, whichmeets the following matters:

-   1. Breakage should be eliminated when a bag inflates and when a    passenger should be protected.-   2. When an automobile collides, gases should flow into necessary    portions of a bag as quickly as possible to inflate stably and    quickly.-   3. In an area (generally, referred to as a protective area), in    which a passenger's head comes into contact with a bag and the head    is protected, inflating portions are easy to set in appropriate    positions in view of a roof design of a vehicle and a passenger's    sitting posture.-   4. It is easy to maintain a predetermined internal pressure for a    predetermined period of time after the bag inflates when bags are    roll over accommodating type bags, which take account of protection    of a passenger in the case where an automobile turns sideways after    lateral collision.-   5. A bag should be lightweight and can be stored compactly.-   6. A predetermined injury criteria can be cleared.

Means for Solving the Problems

The invention provides a curtain bag comprising at least two pieces ofcloth joined to each other at an outer peripheral joint part provided atan outer peripheral edge thereof and at a plurality of dot-like innerjoint parts provided inside the outer peripheral joint part, and whereinthe plurality of dot-like inner joint parts are provided to beindependent of the outer peripheral joint part and independent of oneanother, and provided more densely in a region, which comes into contactwith a pillar portion of an automobile at the time of inflation, than inthe remaining region.

Advantages of the Invention

With a curtain bag according to the invention, dot-like inner jointparts are provided independently of the outer peripheral joint part andof one another and arranged in a region, which comes into contact with apillar portion of an automobile upon inflation, more densely than inremaining regions. Therefore, the small, dot-like inner joint parts arearranged dispersedly, so that gases from a gas generator can bedistributed to inflating portions in a short period of time and so a baginflates stably, non-damagingly, and quickly without an excessive stressconcentration on the outer peripheral joint part and the inner jointparts, thus enabling effectively absorbing an impact on a passenger.Also, such reduction in stress concentration further enables makingoriginal yarn small in fineness, making a woven fabric small in density,and reducing a quantity of coating, so that it is possible to expectcost reduction, lightening, an improvement in capacity of storage for abag. Further, draw and wrinkles generated at a boundary between theouter peripheral joint part and the inner peripheral joint parts, andthe inflating portions are decreased, so that it is possible to decreaseunevenness in coating at the time of coating and erroneous cutting atthe time of cutting.

Further, a portion, by which a passenger's head is protected, isincreased in area, manhour and a period of time for design and testingof a bag can be considerably reduced, it is easy to accommodate for achange in a passenger's sitting posture, and it is possible to inhibit apassenger's body from partially protruding outside a vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] A view showing a first example of a curtain bag according tothe invention;

[FIG. 2] A view showing configuration examples of an inner joint part;

[FIG. 3] A view showing a second example of a curtain bag according tothe invention;

[FIG. 4] A view showing a third example of a curtain bag according tothe invention;

[FIG. 5] A view showing a fourth example of a curtain bag according tothe invention;

[FIG. 6] A view showing a fifth example of a curtain bag according tothe invention;

[FIG. 7] A view showing an example of a textile design about a boundarybetween an inner joint part and an inflating portion;

[FIG. 8] A view showing an example of a textile design inside a boundarybetween an inner joint part and an inflating portion;

[FIG. 9] A view showing an example of a textile design called stripedfabric, or rip-stop;

[FIG. 10] A view showing a jet port of a gas generator (inflator)mounted to a bag;

[FIG. 11] A view showing an example of an inner member;

[FIG. 12] A view showing a further array of an inner member;

[FIG. 13] A view illustrating a direction of warp threads of cloth whichforms a bag;

[FIG. 14] A view showing a textile design about a boundary between aninner joint part used in an embodiment and an inflating portion;

[FIG. 15] A view showing a folded state of a bag used in an embodiment;

[FIG. 16] A view showing a textile design inside a boundary between aninner joint part used in an embodiment and an inflating portion;

[FIG. 17] A schematic view showing a curtain bag used in an embodiment;

[FIG. 18] A schematic view showing a curtain bag used in Comparativeexample;

[FIG. 19] A schematic view showing a conventional curtain bag describedin U.S. Patent Specification No. 60/10,149;

[FIG. 20] A schematic view showing a conventional curtain bag describedin German Utility Model Specification No. 29903409;

[FIG. 21] A schematic view showing a conventional curtain bag describedin U.S. Pat. No. 5,566,977;

[FIG. 22] A schematic view showing a further, conventional curtain bag.

BEST MODE FOR CARRYING OUT THE INVENTION

A detailed explanation of a best mode for carrying out the inventionwill be described.

In a curtain bag according to the invention, at least two pieces ofcloth are joined to each other at an outer peripheral joint partprovided at outer peripheral edge thereof and at a plurality of dot-likeinner joint parts provided inside of the outer peripheral joint part,and the inner joint parts are independent of the outer peripheral jointpart and of one another.

Cloth used for the curtain bag according to the invention comprises awoven fabric and fibers are not specifically limitative but preferablycomprise continuous synthetic fiber such as polyamide yarn, polyesteryarn, etc. In case of using a pyro-type inflator making use of a solidgas generating agent and a hybrid inflator making use of high pressuregases and a solid gas generating agent in combination, Nylon 66 fibersare further preferable since there is a fear of melting due tohigh-temperature gases from a gas generator and residue of combustion.

While original yarn is not specifically limited in fineness, 78 to 940dTex are preferable, and 235 to 475 dTex are further preferable. 78 dTexor higher can withstand a dynamic load applied by gases jetting from agas generator and a thermal load due to high-temperature gases andresidue of combustion in the case where a pyro-type inflator and ahybrid inflator described above are used. Also, 940 dTex or less issatisfactory in terms of strength and includes many points ofintersection of warp threads and weft threads even when being woven inhigh density, so that sieve openings of the outer peripheral joint partand the inner joint parts formed by an internal pressure in operationare hard to generate and there is no fear of outflow of gases from theportions. Also, a woven fabric as finished is thin and lightweight toachieve an improvement in storagebility of a bag.

At the time of weaving, warp threads may be used as they are in the formof original yarn since an ordinary plain weave fabric is produced in thecase where a bag is manufactured in a machine-sewing system, and arepreferably subjected to oiling, waxing, or sizing to be used whenoccasion demands. In case of manufacturing a bag by means of the OPWsystem, sizing is preferably carried out since warp threads and weftthreads in predetermined portions of two pieces of cloth are caused tointersect each other to form the outer peripheral joint part and theinner joint parts while the pieces of cloth are woven at the same time,so that the outer peripheral joint part and the inner joint parts becometwo times in density of weaving that of the inflating portions, a loadon warp threads in weaving is large, yarns are easily napped tofrequently bring about defects of weaving, and cutting of the originalyarns is brought about according to circumstances.

It suffices to select a density of weaving in accordance with thefineness of original yarns as used, such that, for example, 90 to 110 ofwarp threads and weft threads in all/2.54 cm is preferable for 470 dTex,about 125/2.54 cm is preferable for 350 dTex, and about 145/2.54 cm ispreferable for 235 dTex. Such ranges of density of weaving make weavingeasy and achieve an improvement in quality of weaving and grade of awoven fabric. Also, it is possible to withstand a dynamic load appliedby gases jetting from the gas generator and a thermal load.

In case of curtain bags, it is necessary to inflate the bag as quicklyas possible, an in case of roll over accommodating type bags, it isnecessary to maintain a predetermined internal pressure for apredetermined period of time, and a coating processing described lateris preferably performed in order to prevent gases from flowing out apiece of cloth itself, the outer peripheral joint part, and the innerjoint parts. In the ranges of density of weaving described above, aquantity of a coating agent permeating an interior of a woven fabric ismoderate and a continuous coating film to a surface of the woven fabricis easy to form, so that an improvement in gastightness is achieved.

It is not necessarily required that warp threads and weft threads be thesame in density of weaving but a difference in the density may beinvolved taking into consideration an efficiency of weaving or adirection of a dynamic load applied by gases as jetted.

FIG. 1 is a view showing a first example of a curtain bag according tothe invention and FIG. 2 is a view showing configurational examples ofan inner joint part.

As shown in the drawings, the curtain bag according to the inventioncomprises two pieces of cloth joined together at an outer peripheraljoint part 1 provided at an outer peripheral edge thereof and at aplurality of dot-like inner joint parts 2 provided inside of the outerperipheral joint part 1. In addition, the reference numeral 2 a denotesinner joint parts, which assume a shape of a circular dot and arecomparatively small in area, out of the inner joint parts 2 and thereference numeral 2 b denotes inner joint parts, which assume a shape ofa trapezoid with rounded corners and is comparatively large in area.

Particularly, in case of the curtain bag according to the invention, theplurality of dot-like inner joint parts 2 are not consisted of a smallnumber of, for example, several straight lines and curved lines as inconventional curtain bags, but are provided 15 to 160, preferably, 15 to150 in number to be independent of the outer peripheral joint part 1 andof one another. In the case where the dot-like inner joint parts 2 aresmaller in number than 15, it is necessary to make the respectivedot-like inner joint parts 2 extremely large in area in order to make athickness at the time of inflation of the bag appropriate, and so anappropriate inflating portion (a passenger protective area) is notobtained. On the other hand, in the case where the dot-like inner jointparts 2 exceeds 160 in number, it is necessary to make the respectivedot-like inner joint parts 2 extremely small in area in order to make athickness at the time of inflation of the bag appropriate, and there isalso caused a fear that appropriate diffusion of gases is obstructed.

The dot-like inner joint parts 2 in the invention comprise non-inflatingportions formed by integrating two pieces of cloth by means ofintersection, or sewing, or bonding of weaving yarns constituting thetwo pieces of cloth, and include the non-inflating portions in whichupper and lower pieces of cloth are integrated with each other overwhole surfaces of the non-inflating portions and the non-inflatingportions in which the upper and lower pieces of cloth are integratedwith each other at the periphery of the non-inflating portions but arenot integrated with each other inside the periphery. The dot-like innerjoint parts 2 can be formed to be shaped as shown in FIG. 2 as well asbeing formed assuming the shape of a straight line segment and a curvedline segment. The dot-like inner joint parts can be made, for example,circular, elliptical, rectangular, rhombic, or polygonal in shape, orcan assume a shape, in which these shapes are partially changed. Thedot-like inner joint parts 2 in the invention may comprise non-inflatingportions which are obtained by integrating a whole surface of suchshapes by means of intersection or sewing of weaving yarns, ornon-inflating portions which are obtained by integrating only an outerperipheral edge of such shapes by means of intersection or sewing ofweaving yarns and an interior of which is not integrated but notinflated by gases.

The respective dot-like inner joint parts 2 in the curtain bag accordingto the invention preferably have an area of 0.7 cm²/part to 80 cm²/part,further preferably, an area of 3 cm²/part to 13 cm²/part. When therespective dot-like inner joint parts 2 have an area of 0.7 cm²/part orlarger, inflating portions are made moderate, so that a load on theportions is small to lead to less rupture. Also, when the respectivedot-like inner joint parts 2 have an area of 80 cm²/part or less,inflating portions are likewise made moderate, so that a predeterminedinternal pressure is resulted and a thickness at the time of inflationof the bag is made appropriate.

The dot-like inner joint parts 2 may be the same in shape and in areathroughout the bag, or ones being different in shape and in area may bemixedly present. Preferably, the shape and the area of the dot-likeinner joint parts 2 are determined taking into consideration of a sizeof a bag, an output of and a position of a gas generator as used.

The curtain bag shown in FIG. 1 includes a gas inflow port 3, to which agas generator is connected, substantially centrally of an upper portionthereof and an inner joint part 2 b being trapezoidal in shape withrounded corners and being comparatively large in area is provided in thevicinity of and in opposition to the gas inflow port 3. The inner jointpart 2 b functions to distribute gases flowing into the bag through thegas inflow port 3 and preferably has a larger area (an area of 80cm²/part or larger) than the area described above in order toappropriately distribute gases. In addition, the inner joint part 2 bcan assume a shape shown in FIG. 2 or a further shape as well as a shapeof a trapezoid with rounded corners.

Also, in the curtain bag shown in FIG. 1, inner joint parts 2 a having ashape of a circular dot and being comparatively small in area areprovided in and in the vicinity of a portion (a region indicated by Y inthe drawing), which comes into contact with a pillar portion at the timeof inflation, to be distributed densely, preferably, two to ten timesthose in a portion in non-contact with a pillar portion.

In conventional curtain bags, a portion, which comes into contact with apillar portion of an automobile at the time of inflation, is in manycases structured to be partially closed and not to inflate (for example,a region indicated by Y in FIG. 22). When such portion is not closed butstructured to be provided densely with the dot-like inner joint parts 2a as described above, however, it is possible to realize a quality ofcushioning on the portion which comes into contact with the pillarportion owing to a little inflation to improve the protective functionwhile preventing the portion which comes into contact with the pillarportion from excessively inflating to bring about waste of gases anddeformation of the bag. Also, by restricting inflation of the portionwhich comes into contact with the pillar portion, it is made possible tofurther quickly promote uniformity in gas pressure before and after theinflation. In addition, the dot-like inner joint parts 2 a can assume ashape shown in FIG. 2 or a further shape as well as a circular shape.

FIGS. 3 to 6 are views showing second to fifth examples of the curtainbag according to the invention. In FIGS. 3 to 6, the same referencenumerals as those in FIG. 1 denote the same parts or members as those inthe latter.

As described above, the respective dot-like inner joint parts 2 in thecurtain bag according to the invention may be the same or may not be thesame in shape and in area in a bag.

The second example shown in FIG. 3 is one, in which line segment innerjoint parts 2 c are arranged in lower portions forwardly of andrearwardly of a portion which comes into contact with a pillar portionof an automobile.

The third example shown in FIG. 4 comprises a bag of a type, in which agas generator (not shown) is connected to a rear, upper portion of thebag and a gas inflow port 3 is provided in the rear, upper portion ofthe bag. Also, all inner joint parts 2 comprise inner joint parts 2 a inthe form of a circular dot and comparatively small in area. The dot-likeinner joint parts 2 a are arranged in a portion, which comes intocontact with a pillar portion of an automobile at the time of inflation,and in the vicinity of the gas inflow port 3 to be distributed moredensely than in the remaining regions, preferably, two to ten timesthose in the remaining regions. Owing to a state, in which the dot-likeinner joint parts 2 a are arranged, it is possible to obtain functionsof preventing an excessive inflation of a portion which comes intocontact with a pillar portion and appropriately distributing inflowinggases.

The fourth example shown in FIG. 5 comprises a bag of a type, in which agas generator is connected to a rear, upper portion of the bag, and isfundamentally the same as that shown in FIG. 4 except a state, in whichinner joint parts 2 are arranged in the vicinity of a gas inflow port 3.By the way, it is required that when the gas generator operates, gasesflowing from the gas generator be first fed forwardly of the bag tospread the folded bag downwardly. In order to cope with a large loadapplied to the bag at an initial stage of gas inflow and to quickly feedthe jetting gases forward, the inner joint parts 2 are desirablyarranged in the vicinity of the gas inflow port 3 and in positions,which are in parallel to a gas jetting direction and in which gases arenot prevented from jetting forward, to be distributed more densely thanand preferably, two to ten times those in the remaining regions (excepta portion, which comes into contact with a pillar portion of anautomobile at the time of inflation). As a specific example ofarrangement, it is possible to list an arrangement, in which the innerjoint parts are aligned clear of a forward front of the gas inflow port3 and forwardly of a lower end of the gas inflow port 3 in series in alongitudinal direction like the inner joint parts 2 in a regionindicated by Z in FIG. 5.

On the other hand, with a view to preventing gases from jettingextremely forward at an initial stage of operation of a gas generator,distributing a part of inflowing gases downwardly, or further absorbingan impulse to a passenger, it is preferable in some cases to formprotruding joint parts 1′, which partially protrude inside the bag, onan outer peripheral joint part 1 in order to change the shape of the bagafter inflation.

The fifth example shown in FIG. 6 is one, in which inner joint parts 2 ain the form of a circular dot 2 a, a line segment inner joint part 2 c,and an inverted U-shaped inner joint part 2 d are used as inner jointparts 2. The inverted U-shaped inner joint part 2 d is provided in thevicinity of and in opposition to a gas inflow port 3 provided rearwardin an upper portion of a bag to function to distribute gases forwardlyand rearwardly like the inner joint parts 2 b shown in FIG. 1. The innerjoint parts 2 a in the form of a circular dot are provided in thevicinity of a downwardly directed opening of the inverted U-shaped innerjoint part 2 d whereby excessive inflation of a portion which comes intocontact with a pillar portion is restricted.

According to the invention, since the dot-like inner joint parts 2 areindependent of an outer peripheral joint part 1 and the dot-like innerjoint parts 2 are independent of one another, it is possible to set, inparticular, the dot-like inner joint parts 2 so that an arrangement ofthe inner joint parts is not concentrated on the same warp threads orthe same weft threads. Adoption of such arrangement is useful from apoint of view of uniformizing a difference in bending rate of weavingyarns between the outer peripheral joint part 1 and the inner peripheraljoint parts 2, and the inflating portions over all the woven fabric,decreasing draw and wrinkles, hence decreasing unevenness in coating atthe time of coating, and improving an accuracy at the time of cutting.

In case of OPW, the inner joint parts 2 about boundaries between themand inflating portions are not specifically limited in textile design,but it suffices to combine, for example, (a) mat weave, (b) figureddouble weave, and (c) plain weave shown in FIG. 7 and to appropriatelyrepeat them. Also, portions of the inner joint parts 2 except thoseabout the boundaries between them and inflating portions are notspecifically limited in textile design but, for example, stitched doubleweave shown in FIG. 8 is preferable in the point of reduction ofintersection.

Plain weave is normally used for the textile design in the outerperipheral joint part 1, the inner joint parts 2 and the inflatingportions except the boundaries between the joint parts 1, 2 and theinflating portions.

When an automobile collides laterally against another automobile or anobstacle, a window glass is broken and the broken glass piece rarelycauses damage to a bag to tear the same much according to circumstances.In order to reduce the extent of such damage as far as possible, thetextile design in the outer peripheral joint part 1, the inner jointparts 2, and the inflating portions except the boundaries between thejoint parts 1, 2 and the inflating portions is not made a simple plainweave but preferably made one, such as so-called check-striped fabric,or one called rip-stop, in which weaving is done in a state of aligningseveral yarns every predetermined number of warp threads and weftthreads as shown in FIG. 9.

The number of yarns thus aligned is preferably about two or three andwith the larger number than this, clearances between yarns become largeand a coating agent is decreased in surface covering effect. Also, theyarns thus aligned have a clearance of 5 to 30 mm, more preferably, 10to 20 mm. The less the clearance, the larger the clearances betweenyarns, so that a coating agent is decreased in surface covering effect.Also, when the yarns thus aligned have a larger clearance than thatdescribed above, there is produced a less effect of reducing damage to abag by glass pieces.

In the case where the inner joint parts 2 are formed by means of themachine-sewing system, it suffices to stitch two pieces of woven fabricby means of a normal sewing machine, or a so-called pattern sewingmachine, into which a pattern is input to accomplish automatic sewing.At this time, in the case where an air resistance is especiallydemanded, outflow of gases from seams can be prevented by sewing with asealing agent interposed between two pieces of woven fabric.

In the case where the inner joint parts 2 are formed by means of thebonding system, it suffices that bonding be accomplished by applying anadhesive between two pieces of woven fabric and interposing them betweentwo rolls of a press or a rolling mill, which is provided with a heatingmechanism, to apply a compressive force on portions, to which theadhesive is applied. At this time, it does not matter whatever anadhesive is, but a silicon adhesive is used in the case where gasesshould be prevented from flowing out.

In case of OPW, it is preferable to normally weave warp threads by theuse of original yarn, which are subjected to sizing, and subsequently toperform a coating processing in order to improve a bag in airtightness.While being particularly limited, it is preferable to scour the originalyarn by means of a jigger scouring machine or a continuous scouringmachine including a plurality of scouring vessels and washing vesselsfor the purpose of removing an oil and a sizing agent, which adhere tothe original yarn, prior to coating so as to eliminate inhibition ofadhesiveness between a coating agent and a piece of woven fabric. Afterscouring, the woven fabric is dried by a cylinder drier or the like.After being dried, the woven fabric may proceed to a subsequent coatingprocessing as it is, but it is preferable to continuously heat-set thewoven fabric after scouring and drying in order to exercise control ondimension and density of weaving.

On the other hand, with machine-sewn bags, while being not specificallylimited in carrying out the invention, scouring is not necessarilyneeded in case of weaving without sizing of warp threads, but scouringis needed in case of using sized yarns, in which case it is preferableto perform drying or heat-setting after drying in the same manner as inthe OPW system.

While a coating agent and a coating method are not specifically limitedin carrying out the invention, a silicon agent is generally used as acoating agent and coating is normally performed with a knife coater. Anapplication quantity of a coating agent differs according to propertiesof a silicon resin as used, whether a processing is of the OPW system orof machine-sewing system, a bag, which is used assuming only an occasionof lateral collision, and a bag, which is used assuming that anautomobile turns sideways after lateral collision.

While an application quantity is not specifically limited, it ispreferably 20 to 50 g/m² for a bag, which is of machine-sewing systemand of the OPW system and in which turn-over of an automobile is notassumed, and preferably 50 to 150 g/m² for a bag, which is of the OPWsystem and in which protection of a passenger at the time of turn-overof an automobile is assumed.

In the OPW system, a product (bag) is formed by cutting to predetermineddimensions and a predetermined shape with a laser cutter after coating,sewing of an accessory such as a tether for fixation of a bag, andreinforcing a mount to a vehicle body.

In the machine-sewing system, after a woven fabric having been subjectedto coating is cut to predetermined dimensions and a predetermined shape,two pieces of the woven fabric are overlapped together and sewn in apredetermined position. As described above, in the case whereairtightness is specifically demanded, sewing is performed with asealing agent such as silicon coat, etc. sandwiched about seams betweentwo pieces of woven fabric as coated.

According to the invention, since stress generated on a bag isappropriately dispersed and uniformized, there is occasionally no needof applying the same quantity of a coating agent on two both pieces ofwoven fabric, which form a bag as described above. In this case, inorder to reduce or prevent breakage of a bag due to rupture of a windowglass at the time of collision, it is possible to increase a quantity ofa coating agent applied on only a window side and to decrease anapplication quantity of a coating agent applied on a compartment side.By decreasing a quantity of coating on a compartment side, gasesappropriately flow out of a piece of woven fabric to lead to a decreasein an injury criteria of a passenger.

Also, with curtain bags of a system, in which a passenger is protectedonly immediately after mere, lateral collision such as first impact,gases are appropriately held in some cases even without a coating on acompartment side to enable protecting a passenger.

According to the invention, in the case where a bag and a gas generatorof normal sizes are used, there is no need for an inner member 4 shownin FIGS. 1 and 12 and intended for reinforcement and appropriatedistribution of gases in the vicinity of a gas inflow port.

With curtain bags intended for inflation at higher speed and curtainbags for use in large-sized automobiles, in which three rows of seatsfor passengers are provided, however, it is necessary in some cases touse a gas generator of a higher output. Also, with gas generators makinguse of a solid gas generating agent and hybrid type gas generatorsmaking use of a solid gas generating agent and high pressure gases incombination, higher-temperature gases and decomposed residue of ahigher-temperature solid gas generating agent as compared with gasgenerators of high-pressure gas type flow into a bag. In such case, theinner member 4 is preferably provided on the gas inflow port 3 toachieve reinforcement for a dynamic load and a thermal load and further,appropriate distribution of gases.

An inner member 4 shown in FIG. 11 is used for a bag of a type, which isshown in FIGS. 4 and 5, and on a rear and upper portion of which a gasinflow port 3 is provided, and ordinarily called “inner tube”.

Also, an inner member 4 shown in FIG. 12 is used for a bag of a type, inwhich a gas inflow port 3 is provided substantially centrally of anupper portion and which is shown in FIGS. 1, 3, and 6, and ordinarilycalled “inner bag” or “bag-in-bag”. Arrows in FIGS. 11 and 12 indicatedirections, in which gases inflow and outflow.

Also, instead of the inner member 4, it is preferable to apply a largerquantity of a coating agent on an outer peripheral joint part 1 around agas inflow port 3 and on inner joint parts 2 than that in the remainingportions and to stick a patch, on which a sealing agent having a bondingfunction is applied, to a piece of ground fabric, which is smaller inelasticity than the woven fabric of a bag. When this is done, it ispossible to prevent melting of and a decrease in strength of originalyarn, which melting and decrease are caused by sieve opening of thetextile design of a joint part exerted by an inner pressure and outflowof high-temperature gases and decomposed residue of a solid from thesieve opening. An application quantity of the coating agent ispreferably larger by 50% to 150% by weight than that in the remainingportions. With 50% or less by weight, a poor sealing effect is producedand with 150% or larger by weight, the associated portion is madeexcessively thick to lead to a decrease in storagebility.

With conventional OPW curtain bags, that cloth, which forms a bag, iswoven so that warp threads are directed substantially in parallel to alength direction of the bag as shown in FIG. 13( a). In the drawing, Adenotes warp threads and B denotes weft threads.

When a system is operated to permit gases to flow into a bag from a gasgenerator, however, a large tension applies in the length direction ofthe bag, that is, comparatively concentrates on warp threads of thewoven fabric, and in that course, in which the bag inflates downwardfrom a roof of an automobile, a large tension applies in a directionperpendicular to the length direction of the bag, that is, comparativelyconcentrating on weft threads of the woven fabric.

In application of the invention, weaving may be done in a conventionalarrangement, but weaving is preferably done in an arrangement, in whichcloth is arranged so that an angle θ between a line C in parallel to alength direction of a bag and a direction A of warp threads of thatcloth, which form a bag, is made at least 20 degrees but at most 70degrees. For example, assuming that when θ is 45 degrees and tensionapplying in a length direction of a bag immediately after gases inflowis 1, 1/√2 of the tension is distributed to warp threads and weftthreads. Also, when a bag inflates downward, assuming that a forceapplying in a direction perpendicular to the length direction is 1, 1/√2of the tension is likewise distributed to warp threads and weft threads,and an improvement in margin against rupture of a bag is achieved.

Assuming that an angle θ between the length direction of a bag and adirection of warp threads of a woven fabric is 45 degrees, tension isdistributed equally to warp threads and weft threads, and it sufficesthat the angle θ be determined taking account of strength of cutting ofand elasticity of warp threads and weft threads of a woven fabric, orloss due to an arrangement of a bag. Generally, the angle θ ispreferably at least 20 degrees but at most 70 degrees, and the effectdescribed above is decreased outside the range.

Also, with curtain bags of the machine-sewing system, while a plainweave fabric having been subjected to coating is cut to predetermineddimensions, it suffices to determine an arrangement of a lengthdirection of a bag and a direction of warp threads of a woven fabric inthe same manner as described above.

According to the invention, a cloth of low fineness is applicable asdescribed above. Since a cloth of low fineness, however, becomes thinphysically, the cloth becomes low in resistance to rupture of a bag ascompared with cloth of high fineness. In particular, for clothpositioned on a window side, comparing with cloth of low fineness, clothof high fineness is advantageous in terms of damage to a bag caused byfragments of a window glass. In such case, by forming cloth positionedon a compartment side from cloth of low fineness as compared with clothpositioned on a window side, and forming cloth positioned on the windowside from cloth of high fineness as compared with cloth positioned onthe compartment side, it is possible to provide a curtain bag beingexcellent in storagebility as compared with a bag, both sides of whichare formed by cloths of high fineness.

According to the invention, since gases from a gas generator can bedistributed to inflating portions in a short period of time as describedabove, inflation speed of a bag is increased. However, there is a limitto an increase in inflation speed only by the invention. In order toattain a higher speed of inflation, it is effective to adjust a state,in which gases for inflation of a bag jet from a gas generator(inflator). For example, as shown in FIG. 10, in the case where a gasjet port of a gas generator is connected to a rear and upper portion ofa bag, gases are increased in straightness when an open diameter K ofthe gas jet port is made small, so that gases quickly reach an inflatingportion being distant from the gas jet port. In particular, according tothe invention, it is possible to provide a curtain bag, in whichstraight advancing gases generated by a decrease in the open diameter Kof the gas jet port can be appropriately distributed to a predeterminedprotective area owing to an excellent gas dispersing performance andwhich can attain uniform inflation at high speed without generation oflocal inflation by the straight advancing gases.

While the open diameter K of a gas jet port of a gas generator mountedto a bag is dependent upon fineness of a curtain air bag as used or thelike, it preferably ranges from about at least 5 mm to at most 10 mmsince in case of less than 0.5 mm, there is a risk that the gas jet portis clogged by the residue of gases as jetted and in case of over 30 mm,gases immediately after being jetted spread widely. Also, a length N ofa gas jet port connected to a bag is not specifically limited, a shape,in which a tip end is throttled, is preferable in that range, in whichthe ratio N/K is at least 5 but at most 20.

Embodiment

Subsequently, the invention will be specifically described by means ofembodiments and referential examples.

(1) Deployment Test

A cold gas type inflator (maximum pressure 220 kPa in 23.81 tankpressure test) manufactured by Autoliv Company and a bag inner pressuremeasurement sensor were mounted to a testing sample, a bag deploymenttest was conducted, high speed photography of a state, in which a bagdeveloped, was conducted, and changes in bag inner pressure weremeasured. Deployment speeds indicated in TABLE 1 are represented interms of time elapsed until the bag inner pressure reached 60 kPa.

(2) Impactor Test

The inflator and the bag inner pressure measurement sensor, which aredescribed above, were mounted to a testing sample, an impactor test wasconducted by a method prescribed in FMVSS201U method, and a head injurycriteria HIC was found from a head's deceleration.

[Embodiment 1]

Yarns, which were formed from Nylon 66 original yarn manufactured byPolyamide High Performance Company to be 470 dTex in fineness and inwhich the number of single yarns was 144, were used with warp threadsbeing subjected to sizing by a sizing agent having a main component ofpolyacrylic acid to weave a woven fabric having a shape shown in FIG. 6so that the finished density of weaving was made warp 57/2.54 cm andweft 46/2.54 cm by an air-jet loom (manufactured by Dornier Company)mounting thereon a Jacquard machine (manufactured by Stäubli Company).In a bag, segmental inner joint parts 2 c were 16 in number to have alength of 8 cm, a width of 1 cm, and an area of 8 cm², dot-like innerjoint parts 2 a were 10 in number to have an area of 3 cm², invertedU-shaped inner joint part 2 d was 1 in number to have a length of about130 cm, a width of 1 cm, and an area of 130 cm², inflating portions wereof plain weave structure, the respective inner joint parts 2 aboutboundaries between them and the inflating portions were of a structureshown in FIG. 14, and a textile design inside about boundaries betweenthe respective inner joint parts 2 and the inflating portions was madeone shown in FIG. 16.

The woven fabric after weaving was subjected to scouring by a continuousscouring machine and after being dried, it was heat-set at 180° C. forone minute by a pintenter. A silicone resin (Product No. DC3730manufactured by Toray•Dow Corning•Silicone Company) was applied 85 g/m²per one side of the woven fabric, which was subjected to scouring andheat-set, by means of a knife-coating method, the woven fabric washeated at 180° C. for three minutes in a heating furnace, then asilicone surface smoothing agent (Product No. DC3715 manufactured byToray•Dow Corning•Silicone Company) was applied as 10 g/m² per one sideof the woven fabric by a gravure coater, and the woven fabric was dried.

The product as coated was cut to a predetermined shape by a laser cutter(manufactured by Lectra Company), a portion mounted to an automobilebody was subjected to reinforcing seam, and a tether was sewn to make aproduct of curtain bag. Further, the product was folded by means of thesystem shown in FIG. 15 and temporary tacked by a tape to fabricate atesting sample. The deployment test and the impactor test were conductedon the sample.

TABLE 1 indicates results of the tests.

[Embodiment 2]

The same method as that in Embodiment 1 was used to fabricate a bagshaped as shown in FIG. 17 and including dot-like inner joint parts 2 abeing 80 in number to have an area of 3 cm² and a single inner jointpart 2 b disposed just below a gas inflow port 3 and having a height ofabout 7 cm, a width of 31 cm, and an area of 20 cm², and the deploymenttest and the impactor test were conducted on the bag.

TABLE 1 indicates results of the tests.

[Embodiment 3]

The same bag as that in Embodiment 2 and shaped as shown in FIG. 17 andincluding only dot-like inner joint parts 2 a being 160 in number tohave an area of 3 cm² was fabricated, and the deployment test and theimpactor test were conducted on the bag.

TABLE 1 indicates results of the tests.

[Embodiment 4]

The same testing sample as that in Embodiment 2 was tested under thesame conditions as those in the Embodiment 2 except that a head centerwas downwardly offset 20 mm relative to a normal position in theimpactor test.

TABLE 1 indicates results of the test.

[Embodiment 5]

Yarns, which were formed from Nylon 66 original yarn manufactured byAsahi Kasei Chemicals Company to be 470 dTex in fineness and in whichthe number of single yarns was 72, were used by the method described inEmbodiment 1 to fabricate a bag shaped as shown in FIG. 17 so as toprovide 63/2.54 cm in finished density, and the deployment test and theimpactor test were conducted on the bag.

TABLE 1 indicates results of the tests.

COMPARATIVE EXAMPLE 1

The same method as that in Embodiment 1 was used to fabricate a bagbeing a conventional product shaped as shown in FIG. 18 and includingfive inner joint parts 102 continuous to an outer peripheral joint part101, and the deployment test and the impactor test were conducted on thebag.

TABLE 1 indicates results of the tests.

TABLE 1 Shape Damage Deployment Head injury of bag of bag speed criteria(HIC) Embodiment 1 FIG. 6 None 25 200 Embodiment 2 FIG. 17 None 20 200Embodiment 3 FIG. 17 None 22 240 Embodiment 4 FIG. 17 None 20 280Embodiment 5 FIG. 17 None 18 180 Comparative FIG. 18 None 30 200-280Example

As indicated in TABLE 1, a multiplicity of the independent inner jointparts 2, by which a shape of inflating portions is defined when a bagaccording to the invention inflates, are arranged whereby the bag isconsiderably increased in deployment speed as compared with conventionalbags. Also, a head injury criteria HIC of a passenger obtained as aresult of the impactor test is considerably lower than HIC<1000, whichis a injury reference limit prescribed in the regulations, of course, incase of collision in a normal position prescribed in test standards andeven in case of being offset 200 mm from a normal position, and so it isapparent that the bag is effective also in protecting a passenger's headnot seated in a normal position.

INDUSTRIAL APPLICABILITY

The invention is effective in an apparatus, which protects a passengerin an automobile when the automobile suffers lateral collision. Further,the invention is also applicable in other protective apparatuses such asa side bag, which is accommodated in a seat or a door to protect apassenger's side, a pedestrian protective bag, and an air bag formotorcycles.

DESCRIPTION OF REFERENCE NUMERALS

-   1 outer peripheral joint part-   2 inner joint part-   2 a inner joint part of a shape of a circular dot-   2 b inner joint part of a shape of a trapezoid with rounded corners-   2 c line segment inner joint part-   2 d inverted U-shaped inner joint part-   3 gas inflow port-   4 inner member

The invention claimed is:
 1. A curtain bag comprising at least twopieces of cloth joined to each other at an outer peripheral joint partprovided at an outer peripheral edge thereof and at a plurality of innerdot joint parts provided inside the outer peripheral joint part,characterized in that the plurality of inner dot joint parts arearranged dispersedly across the entire region of the curtain bag, andprovided to be independent of the outer peripheral joint part andindependent of one another, and provided more densely in a region, whichcomes into contact with a pillar portion of an automobile at the time ofinflation, than in other regions.